Effect of Change Angulation and Material of Mini-screw inserted in Retro Molar Pad Area on Stress Distribution: A Finite Element Simulation Study This study evaluated the influence of angulation and material composition on the stress distribution and displacement of mini-screws placed in the retromolar pad area using finite element analysis; these mini-screws inserted in the retromolar pad area were referred to as MRM. A 3D mandible model was generated from CT scan data using Mimics and 3-Matic software, while the mini-screw was modelled in AutoCAD. Finite element analysis was performed with Inventor Professional software. A 2 N force, parallel to the occlusal reference line (ORL), was applied to MRM at insertion angles of 0°, 15°, 30°, 45°, and 60° relative to the ORL. Three MRM materials were analysed: stainless steel (SS), titanium alloy (Ti-6Al-4V), and pure titanium (Ti). Results revealed that the lowest Von Mises stresses occurred at a 0° insertion angle, while the highest stresses were observed at 60°. Stress levels were comparable across materials at 0°, 15°, and 30°, but SS MRM generated higher stresses than titanium materials at 45° and 60°. Displacement analysis indicated that SS MRM had the lowest displacement, while Ti MRM exhibited the highest across all angles. Importantly, all stress values remained below the bone’s yield strength, and displacements were clinically insignificant. For optimal stability, a 0° insertion angle is recommended, with 15° and 30° serving as viable alternatives. These findings provide guidance on selecting mini-screw angulation and materials for effective orthodontic anchorage in the retromolar pad area.

Background: Obesity and overweight are strong independent risk factors for chronic kidney disease (CKD). Using serum creatinine-based estimated glomerular filtration rate (eGFR) equations in these subjects may be inaccurate. On the other hand, cystatin C–based eGFR equations may overestimate CKD prevalence as recent findings suggest an association of cystatin C with obesity. The objective of this study was to assess the accuracy of a cystatin C–based eGFR equation compared to two creatinine –based eGFR equations in overweight and obese subjects. Methods: This was a prospective cross-sectional study which recruited healthy volunteers aged 18-55 years with a body mass index (BMI) ≥ 23kg/m² (Asia Pacific Guidelines). Their renal profiles, serum cystatin C and 99m technetium diethylene triamine pentacetic acid (⁹⁹mTc-DTPA) scans were performed on the same day. The correlations and accuracy of the creatinine-based and cystatin C-based eGFR equations with the ⁹⁹mTc-DTPA GFR were determined. Results: One hundred and one subjects with a median age of 30.0 (27.0-43.5) years and mean BMI of 28.7 ± 4.5 kg/m2 were recruited. The cystatin C-based eGFR equation showed the best correlation with the ⁹⁹mTc-DTPA GFR (r=0.526, p=0.001) and was more accurate in measuring abnormal GFR compared to the creatinine-based eGFR equations. Conclusion: Our study showed that the cystatin C-based eGFR equation was more accurate, sensitive and specific in overweight and obese subjects compared to the creatininebased eGFR equations.